The car seems to run fine but I had her running on a "barely running" idle, and the oil pressure light would flicker when it was in gear and held at stop by the brake (but only when driven for over an hour). I bumped up the idle 100-300RPM (hard to say when you only have your ear to judge), and it no longer does this. When it was doing it it would barely move forward at all on idle on the flat. Now it moves forward but very slowly. I drive 50 hard miles every night with nary a problem, so is my light possibly over sensitive or do I have an issue here?

At very low RPMs, the oil light will flicker on. That's normal. A "barely-running" idle is not normal; realistic engine idle speeds with a stock or near-stock camshaft start at 600 RPM and go up to about 800, depending on exact setup, emissions equipment, transmission, etc.

Some of the oil pressure senders are more sensitive than others, and when they're screwed into the oil gallery at the rear of the RH side of the block, they "run out" of oil sooner than when they're screwed into the oil pump itself.

Something like that happened to me in my 71 Valiant Duster, it was a bulb and resistor that make the problem start when running the engine a couple of minutes, i got those parts replaced and problem solve!

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Mopar Muscle is well defend by Slant Six!

Valiant Duster 1971

When me and my buddies were young and dumb,We just put a piece of electrical tape over the light so we would'nt see it!!